The present invention relates to an ink supplying apparatus that supplies ink from a cartridge to a recording head for discharging the ink.
Conventionally, as an ink supplying apparatus that supplies ink in an exchangeable ink cartridge to a recording head and also warns a fact that the ink cartridge becomes empty, an apparatus disclosed in Japanese Patent Application Laid Open No. 11-91121 (1999) is known. This apparatus is designed such that a sub-tank is placed in a supply path of the ink between the ink cartridge and the recording head, and the ink in the ink cartridge can be supplied to the sub-tank by using a pump. Also, a liquid surface level sensor for detecting an ink liquid surface level is provided in the sub-tank. Then, if the ink liquid surface level detected by the liquid surface level sensor becomes a predetermined level or less, the pump is used to supply the ink from the ink cartridge to the sub-tank. Even if the pump is driven, if the ink liquid surface level detected by the liquid surface level sensor is the predetermined level or less, the ink cartridge is judged to be empty, and a warning for urging a user to exchange the ink cartridge is issued.